~ Stuff I Learned About Tech+Hydroponics

Build Log for January 24th

I started watching the video Managing Nutrient Solutions for Hydroponics Part 1. As the speaker notes:

NFTs have their disadvantages…

A Better Future Design

Detects clogged emitters and a broken pump.

Today

I’ll continue where I left off:

Measure CO2 and log readings. Take measurements for at least one hour. Take measurements every 1 minute. If the log file can’t be written to, stop the program because logging right now is the UI and I’m trying to understand results of CO2 measurements. Wrote CO2ReadAndLogTest.ino. DONE. Running Test at The Grow Station.

Got 228 readings. Average = 653. Median = 648. While this is a somewhat brief test ( 228 mins * 1 hour/60 mins = 3 hours, 48 mins), median is close to average – not much drift. As I noted in this build log, I plan to adjust the MHZ-16 sensor reading to the Extech CO2 meter reading (of 580ppm). I will do this by subtracting 60ppm from the MHZ-16 reading within the firmware.

Here’s a test run with output on the serial monitor:

The water pump worked great. 2 minutes every 30 minutes results in the rock wool being extremely wet all the time. I will test with an adjusted 2 minutes every hour. Luckily, the Timer library uses unsigned long for setting milliseconds which means the maximum number is 4,294,967,295. I will set ms = 3,600,000. The updated RelayTest.ino is located here. OK. Arduino code uploaded and pump restarted.

Adjust CO2 to ~ 1,200ppm.

write and test Arduino code to give me a feel for adjusting the CO2 level. I’ve never used a CO2 canister or adjusted the CO2 level. So this has to be simple. The area I will adjust is the Grow Chamber. I’ll mount the fan holder and set up the fan going with the CO2 such that the setup is the same as when the Grow Chamber will be in use. One challenge I am concerned about is CO2 leakage. The Grow Chamber is not sealed. So the CO2 can easily leak out. The question I have is does the CO2 immediately dissipate through these leaks? Or are some leaks ok to have?

I decided to solder on a female barrel connector onto the + and – wires of the fan. I am challenged to remember the wiring. I used the info on wiring from this page:

must have a 2.1mm power plug on the Arduino end, and

the plug must be “centre positive”, that is, the middle pin of the plug has to be the + connection.

Here’s a picture of an adapter ideally suited to powering the Arduino. The important info is underlined in red here:As you can see, it has all the right stuff: 12V, DC, and a little picture that shows you that the middle pin is positive. Actually, I nixed the idea of using a barrel jack and ended up using a connector I got awhile back

run test.

I took me awhile to get the fan going and dabble with the CO2 setup. I’ll start tests tomorrow.